This invention relates generally to sleeping bags, and more specifically to a sleeping bag with at least one stretchable panel comprising at least part of its outer layer.
Consumers face a difficult task in finding a sleeping bag that is both thermally efficient and comfortable. Mummy bags, which generally minimize internal volume, are shaped with a lateral taper to approximately contour the body of a user. These bags effectively conserve heat by decreasing air movement within the bag. As a result, mummy-type sleeping bags are well suited for use in outdoor, cold ambient temperatures. A drawback to mummy bags is that some people feel discomfort because the relatively snug fit of these bags reduces their range of motion making them feel confined. The feeling of discomfort is typically heightened if parts of the user's body that are often moved, especially during sleep, such as the shoulders, elbows and knees, are confined.
Rectangular-type sleeping bags are shaped with a generally constant lateral dimension and provide generally a larger range of motion. Although rectangular bags are generally more spacious than mummy bags, a drawback is that their larger internal volumes make them thermally inefficient. As a result, rectangular bags are well suited for use indoors or in milder outdoor temperatures. When used in colder environments, users of rectangular bags can more easily become chilled, especially toward their feet.
Unfortunately, no single sleeping bag is available that is both thermally efficient and permits relative freedom of movement, particularly in the regions of the bag corresponding to the shoulders, knees and elbows of a user.